RU2424270C2 - Zirconium cross-linking compositions and procedures of their utilisation - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: cross-linking composition includes tri-ethanol-amine of zirconium, tetra(hydroxi-alkyl)ethylene-diamine, water and, not necessarily, multi-atom alcohol. There are also disclosed procedures, including utilisation of above said composition for hydraulic break, and also for blocking penetrable zones and seepage in underground formations.

EFFECT: raised efficiency at oil extracting operations with cross-linking compositions in most hot and deep wells.

13 cl, 17 ex, 3 tbl

Description

FIELD OF THE INVENTION

The invention relates to crosslinking compositions comprising a zirconium complex, and to the use of zirconium crosslinking compositions in oil field applications, such as in hydraulic fracturing and clogging of permeable zones.

BACKGROUND OF THE INVENTION

The production of oil and natural gas from underground wells (underground formations) can be stimulated using a method called hydraulic fracturing, in which a viscous fluid composition (fracturing fluid) containing a suspended proppant (e.g. sand, bauxite) is introduced into an oil or gas a well through pipes, such as a piping system or casing, at flow rates and pressures that create, renew, and / or increase crack sizes in an oil or gas containing mold and. The proppant is introduced into the fracture region by introducing a fluid composition and prevents clogging of the formation after the pressure decreases. The leakage of the fluid composition into the formation is limited by the viscosity of the fluid composition. The viscous fluid also makes it possible to suspend the proppant into the composition during the fracturing operation. Crosslinking agents, such as borates, titanates or zirconates, are usually included in the composition for adjusting viscosity.

Typically, less than one third of the available oil is recovered from the well after gaps have been formed in the well and before production productivity decreases at the point where oil recovery becomes economically unprofitable. Enhanced oil recovery from such subterranean formations often includes attempts to move the remaining crude oil together with the working fluid, such as gas, water, brine, steam, polymer solution, foam or micellar solution. Ideally, such methods (commonly referred to as flooding methods) provide for the movement of the oil to be extracted at a substantial depth into the production well; however, in practice this often does not happen. The oil reservoir is usually heterogeneous, with some parts of it being the most permeable compared to other parts. As a result, regulation of a certain direction often enough happens in such a way that the working fluid preferably flows through exhausted oil zones (the so-called "auxiliary zones"), and not through those parts of the reservoir that contain enough oil to make recovery operations oil profitable.

The difficulties encountered in recovering oil due to the high permeability of the zones can be corrected by pumping an aqueous solution of an organic polymer and a crosslinking agent into certain subterranean formations under conditions where the polymer will crosslink to form a gel, thereby reducing the permeability of such subterranean formations with respect to to working fluid (gas, water, etc.). Polysaccharide-based or partially hydrolyzed polyacrylamide-based fluids crosslinkable with certain compounds based on aluminum, titanium, zirconium and boron are also used in these operations to increase recoverable oil volumes.

Crosslinked fluids or gels, one way or another used to fracture an underground formation or to reduce the permeability of an underground formation, are now used in the hottest and deepest wells with varying pH values, where crosslinking speeds with known crosslinking compositions may be unacceptable. Preference is given to developing new crosslinking agents for these new conditions, and oil producers that provide well production services can add inhibiting agents that effectively delay the crosslinking of a particular metal crosslinking agent under these conditions.

A number of patents disclose the use of various retarding agents in combination with specific crosslinking agents for which they are effective. These patents typically indicate the addition of one or more ingredients to the crosslinking composition or indicate special operating conditions, such as a narrow pH range. These are just a limited number of disclosed retarding agents suitable for titanium and zirconium crosslinking agents. Thus, the used retarding agents with titanium and zirconium crosslinking agents have limited elasticity for use in servicing oil production wells to stimulate or increase the volume of produced oil and gas from a well or other underground formation.

Therefore, there remains a need to use an effective crosslinking agent, which is useful in oil production operations, such as hydraulic fracturing and clogging of permeable zones and seepages in a certain range of pH values. There is also a need to regulate the crosslinking speed in order to ensure the elasticity of the crosslinking agent, in such a way as to provide a range of crosslinking speeds and, possibly, within a certain range of pH values, crosslinking conditions with a single crosslinking agent. The presented invention meets these needs.

SUMMARY OF THE INVENTION

This invention provides a crosslinking composition comprising a zirconium triethanolamine complex, tetra (hydroxyalkyl) ethylenediamine, water and optionally a polyhydric alcohol. The zirconium complex may be, for example, bistriethanolamine zirconate or tetratriethanolamine zirconate. The composition may further include a retention agent, which is hydroxyalkylaminocarboxylic acid. The composition may also further comprise an crosslinkable organic polymer.

In the case where the composition contains a polymer, the composition is suitable in the field of oil production applications, such as in the method of hydraulic fracturing of an underground formation and in the method of plugging permeable zones or seeping into an underground formation. It has unexpectedly been found that the composition of this invention is effective when used in such methods in which the pH can vary in the pH range from 3 to 12, in the temperature range and under other conditions. The retention time can be controlled in order to ensure elasticity by adjusting the appropriate amounts of components, including a crosslinking agent and delaying agents.

This invention provides a method for fracturing a subterranean formation, which comprises introducing into the subterranean formation a crosslinking composition comprising a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and an organic polymer capable of crosslinking, and possibly a polyhydric alcohol, at a flow rate and pressure sufficient to create, re-open and / or enlarge one or more cracks in the subterranean formation. The constituent parts of the crosslinking composition may be mixed prior to their introduction into the formation, or the components may be introduced and reacted in the formation after a certain controlled period of time.

This invention provides a method for selectively clogging permeable zones and seepages in a subterranean formation, which comprises introducing into the permeable zone or subsurface seepage a crosslinking composition comprising a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and a crosslinkable organic polymer, and optionally polyhydric alcohol. A pH buffer that maintains a specific pH and a retention agent, which is hydroxyalkylaminocarboxylic acid, or both, may be mixed into the crosslinking composition before the composition is introduced into the permeable zone or percolation site.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a composition comprising a zirconium based crosslinking agent, which is a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine and water. By varying the molar ratio between the zirconium complex and hydroxylamine in combination with additional components such as polyhydric alcohol, a retarding agent, etc., a number of zirconium-based compositions can be made, and these compositions are effective as crosslinking agents in the range of values pH 3-12.

The zirconium complex is a zirconium triethanolamine complex, such as bistriethanolamine zirconate or tetratriethanolamine zirconate. A preferred complex of zirconium triethanolamine is tetratriethanolamine zirconate. Tetratriethanolamine zirconate can be rapidly prepared by methods known to those skilled in the art. Alternatively, tetratriethanolamine zirconate is commercially available from E.I. du Pont de Nemours and Company, Wilmington, DE under the name Tyzor® TEAZ organic zirconate.

The tetra (hydroxyalkyl) ethylenediamine preferably has the formula R ¹ (R ² ) —N — CH ₂ —CH ₂ —N′ — R ³ (R ⁴ ), where R ¹ , R ² , R ³ and R ^{4 are} independently selected from the group consisting of hydroxyethyl, hydroxy-n-propyl or hydroxyisopropyl groups. More preferably, the tetra (hydroxyalkyl) ethylenediamine is selected from the group consisting of N, N, N ', N'-tetrakis- (hydroxyisopropyl) ethylenediamine and N, N, N', N'-tetrakis- (2-hydroxyethyl) ethylenediamine and their combinations. Most preferred is N, N, N ', N'-tetrakis- (hydroxyisopropyl) ethylenediamine, which is commercially available from, for example, BASF Corporation, Mount Olive, NJ under the name Quadrol® polyol.

The crosslinking composition typically contains from about 0.01 to about 5 mol of tetra (hydroxyalkyl) ethylenediamine and from about 0.01 to about 10 mol of water per mole of zirconium triethanolamine complex. Preferably, the composition contains from about 0.25 to about 2.0 mol of tetra (hydroxyalkyl) ethylenediamine per mole of zirconium triethanolamine complex. Preferably, the composition contains from about 1.0 to about 5.0 moles of water per mole of zirconium triethanolamine complex.

Optionally, the composition may include a polyhydric alcohol. The addition of a polyhydric alcohol has an effect on the crosslinking rate of the crosslinkable organic polymer by the composition. Preferably, the polyhydric alcohol is selected from the group consisting of glycerol, 1,1,1-tris (hydroxymethyl) ethane, 1,1,1-tris (hydroxymethyl) propane, pentaerythritol and sorbitol. More preferably, the polyhydric alcohol is glycerol.

The amount of polyhydric alcohol is typically taken from about 0.0 to about 5.0 mol, preferably from about 0.5 to about 2.0 mol, per molecule of the zirconium triethanolamine complex.

The composition may further include a retention agent, which is hydroxyalkylaminocarboxylic acid. Preferably, the composition comprises a retarding agent, the retarding agent being selected from the group consisting of bishydroxyethylglycine, bishydroxymethylglycine, bishydroxypropylglycine, bishydroxyisopropylglycine, bishydroxybutylglycine, monohydroxyethylglycine and glycine. The most preferred retention agent is bishydroxyethyl glycine.

The composition may also further include an crosslinkable organic polymer. Examples of suitable crosslinkable organic polymers include soluble polysaccharides, polyacrylamides and polymethacrylamides. Preferably, the organic polymer is a soluble polysaccharide that is selected from the group consisting of gums, gum derivatives and cellulose derivatives. Gums include guar gums and gums contained in the cortex of pseudoacacia robinia, as well as other gums, galactomannans and glucomannans, contained in the juice of the eucalyptus tree, and such as those that stand out from the trees of the Cesalpinium family - cassia, Brazilian tree, Cesalpinia spiny, honey acacia, karaya gum tree and the like. Derivatives of gums include hydroxyethyl guar (HEG), hydroxypropyl guar (HPG), carboxyethyl hydroxyethyl guar (CEHEG), carboxymethyl hydroxypropyl guar (CMHPG), carboxymethyl guar (CMG) and the like. Cellulose derivatives include compounds that contain carboxy groups, such as carboxymethyl cellulose (CMC), carboxymethyl hydroxyethyl cellulose (CMHEC) and the like. Soluble polysaccharides can be used individually or in combination; usually, however, individual material is used. Guar derivatives and cellulose derivatives such as HPG, CMC and CMHPG are preferred. HPG is in most cases more preferable on the basis that it is commercially available for sale and possesses the desired properties. However, CMC and CMHPG may be more preferred in crosslinking compositions when the pH of the composition is less than 6.0, or higher than 9.0, or when the permeability of the formation is such that it is necessary to maintain the residual solid compounds at a low level to prevent fracture of the formation.

A polymer that is crosslinkable is mixed under normal conditions with a solvent, such as water or a water / organic solvent mixture, or with an aqueous solution in order to form a base gel. Organic solvents that can be used include alcohols, polyols, hydrocarbons such as diesel. By way of example, the polymer may be mixed with water, a water / alcohol mixture (for example, one where the alcohol is methyl alcohol or ethyl alcohol) or an aqueous solution comprising a clay stabilizer. Clay stabilizers include, for example, hydrochloric acid and chlorides, such as tetramethylammonium chloride (TMAC) or potassium chloride. Aqueous solutions, including clay stabilizers, may contain, for example, 0.05-0.5 wt.% Stabilizer, based on the total weight of the crosslinking composition.

The composition may include an effective amount of a buffer solution for adjusting the pH of the medium. The pH buffer may be acidic, neutral or alkaline. The pH buffer is typically capable of adjusting the pH from about pH 3 to about pH 12. For example, in a composition where a pH of about 4-5 is used, an acetic acid based buffer solution may be used. In the composition, when a pH value of about 5-7 is used, a fumaric acid buffer solution or a sodium diacetate buffer solution can be used. In the composition, when a pH value of about 7-8.5 is used, a sodium bicarbonate buffer solution can be used. In the composition, when a pH value of about 9-12 is used, a buffer solution based on sodium carbonate or sodium hydroxide can be used. Other suitable buffer solutions that may be used are known to those skilled in the art.

The composition may also contain optional components, including those that are conventional additives in oil fields of application. Such compositions may also include one or more proppants, friction reducing agents, bactericides, hydrocarbons, chemical breakers, stabilizers, surfactants, formation control agents, and the like. Proppants include sand, bauxite, glass beads, nylon granules, aluminum granules, and the like. Substances that reduce friction include polyacrylamides. Hydrocarbons include diesel. Chemical destroyers destroy the crosslinked polymer (gel) in a controlled manner and include enzymes, alkali metal persulfate, ammonium persulfate. Stabilizers include methyl alcohol, alkali metal thiosulfate, ammonium thiosulfate. Stabilizers may also include clay stabilizers such as hydrochloric acid and chlorides, for example tetramethylammonium chloride (TMAC) or potassium chloride.

These optional components are added in effective amounts sufficient to achieve the desired crosslinking properties based on the individual components, the desired delay during crosslinking, temperature and other conditions that must be taken into account when breaking the formation or clogging the permeable zones.

A crosslinking composition is prepared by mixing a complex of zirconium triethanolamine with tetra (hydroxyalkyl) ethylene, water and optional components in any order. For example, in private applications in the oil field, the zirconium triethanolamine complex may be pre-mixed with tetra (hydroxyalkyl) ethylenediamine, water and, optionally, polyhydric alcohol and introduced into the formation. The crosslinkable organic polymer can be introduced into the formation in a separate stream. Alternatively, all components may be premixed and incorporated into the subterranean formation in a single stream. It is advantageous when the components can be mixed in various combinations, and more advantageous when the components can be mixed immediately before use, which makes it easy to vary and adjust the crosslinking speed.

In those cases where the composition comprises a polymer, the composition is suitable in oil producing applications, such as in a method for fracturing a subterranean formation and in a method for plugging permeable zones or seepage in a subterranean formation.

Thus, this invention provides a method for fracturing a subterranean formation, which comprises introducing into the subterranean formation a crosslinking composition comprising a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and a crosslinkable organic polymer and, optionally, a polyhydric alcohol, a retention agent, a pH buffer, and combinations of two or more of them at a flow rate and pressure sufficient to create, re-open and / or enlarge one or more cracks in the subterranean formation.

In a first embodiment of a method for hydraulically fracturing an underground formation, a crosslinking composition and a crosslinkable polymer are initially contacted prior to being introduced into the formation, such that the crosslinking agent and the polymer react to form a crosslinked gel, and the gel is introduced into the formation. In this method, a crosslinking composition is prepared by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and, optionally, a polyhydric alcohol. A base gel is prepared by mixing a crosslinkable organic polymer with a solvent, the solvent being water or a water / organic solvent mixture, or mixed with an aqueous solution. This method further includes contacting the crosslinking composition with a base gel; allowing the crosslinking composition and base gel to react to form a crosslinked gel and introducing the crosslinked gel into the formation at a flow rate and pressure sufficient to create, re-open and / or enlarge a crack in the formation. The crosslinking composition, base gel or both components may further include a crosslinking retarding agent and / or pH buffer.

Alternatively, the subterranean formation may be drilled by the borehole such that contacting the crosslinking composition with the base gel occurs in the borehole and the crosslinked gel is introduced into the formation from the borehole. This method of fracturing a subterranean formation through a borehole includes (a) preparing a crosslinking composition by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and, optionally, polyhydric alcohol; (b) preparing a base gel by mixing the crosslinkable organic polymer with a solvent, the solvent being water or a water / organic solvent mixture, or mixed with an aqueous solution; (c) introducing a base gel into a borehole; (d) simultaneously with or sequentially after, introducing a base gel into a borehole, introducing a crosslinking composition into the borehole; (e) allowing the base gel and crosslinking agent to react to form a crosslinked aqueous gel; and (f) introducing the crosslinked gel into the formation through a borehole at a flow rate and pressure sufficient to create, re-open and / or enlarge a fracture in the formation. The pH buffer, a retention agent, which is hydroxyalkylaminocarboxylic acid, or both, can be independently mixed with the base gel, the crosslinking composition, or both, before the base gel and crosslinking composition are introduced into the borehole.

After the formation of a gap or discontinuities, the method may further include introducing a crosslinking composition comprising a zirconium triethanolamine complex, tetra (hydroxyalkyl) ethylenediamine, water and a crosslinkable organic polymer, a proppant, and optionally a polyhydric alcohol in the area of the formation of discontinuity or breaks. This secondary administration of the crosslinking composition is preferably feasible when the crosslinking composition is used to create a tear or tears that does not contain a proppant. The crosslinking composition may be sequentially (then) removed from the formation.

Another use of the crosslinking composition of the present invention relates to a method for selectively clogging permeable zones and seepage in a subterranean formation, which comprises introducing into the permeable zone or subterranean seepage region a crosslinking composition containing a zirconium triethanolamine complex, tetra (hydroxyalkyl) ethylene diamine, an organic polymer capable of stitching, water, and optionally polyhydric alcohol, into a permeable zone or underground seepage area. A pH buffer, a retention agent, which is hydroxyalkylaminocarboxylic acid, or both, may be mixed with the crosslinking composition before introducing the crosslinking composition into the permeable zone or percolation site.

In a first embodiment of a method for selectively plugging a permeable zone or infiltrating a subterranean formation, an organic polymer capable of crosslinking and the crosslinking composition are precontacted before they are introduced into the underground formation so that the polymer and the crosslinking agent interact to form a crosslinked aqueous gel — a gel that then introduced into the formation.

In an alternative embodiment of the method of plugging a permeable zone or seeping into a subterranean formation, the crosslinking composition and an organic polymer capable of crosslinking are introduced separately from each other either simultaneously or sequentially into the permeable zone or subterranean seepage region so that crosslinking occurs within the subterranean formation. This method includes (a) preparing a crosslinking composition by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and, optionally, a polyhydric alcohol; (b) preparing a base gel by mixing the crosslinkable organic polymer with a solvent, the solvent being water or a water / organic solvent mixture, or mixed with an aqueous solution; (c) introducing a base gel into a permeable zone or an area of underground seepage; (d) simultaneously with or sequentially thereafter, introducing a base gel into a permeable zone or underground seepage area, introducing a crosslinking composition into a permeable zone or underground seepage area; (e) allowing the base gel and the crosslinking agent to react to form a crosslinked aqueous gel to clog the area and / or leak out.

The relative amounts of crosslinkable organic polymer and crosslinking composition may vary. Small but effective amounts are used, which will vary depending on the conditions, for example, the type of subterranean formation, the depth at which the method (for example, fluid fracturing, clogging of permeable zones or clogging of seepage) should be carried out, temperature, pH, etc. . In most cases, only small amounts of each of the components are used, as far as they will provide the necessary level of viscosity to achieve the desired result, that is, the formation of faults in the underground formation or clogging of permeable zones or seepages to the extent necessary to promote adequate extraction of oil or gas from the formation.

For example, suitable gels can typically be prepared for fluid fracturing by using an organic polymer capable of crosslinking in amounts of up to about 1.2 wt.% And a crosslinking composition in amounts of up to about 0.50 wt.% Complex of zirconium triethanolamine, with a percentage ratio based on total weight. Preferably, about 0.25 to about 0.75 wt.% Crosslinkable organic polymer is used, and about 0.05 to about 0.25 wt.% Zirconium triethanolamine complex is used.

In the method for plugging permeable zones or seepages, in most cases about 0.25 to 1.2% by weight of crosslinkable organic polymer is used, preferably from 0.40 to 0.75% by weight of the total weight. Typically, about 0.01 to 0.50 wt.% Of the zirconium triethanolamine complex is used, preferably 0.05 to 0.25 wt.% Of the total weight.

The amount of the zirconium triethanolamine complex used with respect to the crosslinkable organic polymer is such that it provides a concentration of zirconium ions in the range of from about 0.0005 wt.% To about 0.1 wt.% Of the total weight. The preferred concentration of zirconium ions is in the range of about 0.001-0.05% by weight of the total weight.

A typical crosslinking composition in this invention can be used at a pH of from about 3 to 11. For low temperature applications (150-250 ° F, 66-482 ° C), activating carbon dioxide based fluids can be used. In this case, the preferred pH for the crosslinking composition is a pH of from about 3 to about 6. For high temperature applications (300-400 ° F, 149-204 ° C), the preferred pH is a pH of from about 9 to about 11. A crosslinking composition selected for use, will vary with the pH used.

Examples

Test methods

Base Gel Preparation

One liter of tap water was added to the Waring homogenizer equipped with three jars with paddle mixers. Stirring was started and 3.6 g of the polysaccharide polymer was added, followed by the addition of a clay stabilizer (tetramethylammonium chloride) and a buffer solution selected to establish a pH of 4.0-7.0. The stirring speed was set to maintain a light vortex while stirring in the upper part of the solution, and stirring continued for 30 minutes, resulting in "30 pounds / 1000 gallons" of base gel. After 30 minutes of stirring, the pH of the base gel was adjusted to the desired final pH using (1) acetic acid buffer solution for pH 4-5; (2) a buffer solution based on fumaric acid or based on sodium diacetate for pH 5-7; (3) a sodium bicarbonate buffer solution for pH 7-8.5; or (4) a sodium carbonate or sodium hydroxide buffer solution for pH 9-11. Stirring was stopped, and the base gel was left to settle for 30 minutes.

Alternatively, for “20 pounds / 1000” gallons of base gel, 2.4 g of polymer was added to one liter of tap water. For a “60 lb / 1000” gallon base gel, 7.2 g of polymer was added to one liter of tap water.

Whirlwind Test

A portion of the 250 ml base gel was measured into a clean Waring homogenizer with shaking. Stirring began, and the speed was set to create a vortex by the actions of the clutch blade. The agitation speed set for the controlled control was recorded and kept constant for all tests in order to evaluate reproducibility. The amount of cross-linking agent was pumped into the extreme part of the vortex of the stirred base gel, and a stopwatch was immediately started, which showed a time equal to 0 at the initial moment of measurement. When the gel viscosity increased enough to allow fluid to cover the sleeve on the homogenizer blade and the vortex stopped, time was recorded. This time, which is the difference between the start time of the stopwatch, and the time when the vortex stops, is the time the vortex stops. If the vortex was not stopped within 10 minutes, then the test was terminated, and the vortex termination time of more than 10 minutes was recorded. The initial and final pH of the crosslinked gel were also recorded as pHb and pHf, respectively. Such vortex cessation tests provide a means of obtaining a reasonably good estimate of the required time to complete crosslinking of the polymer with a crosslinking agent. Complete cessation of the vortex indicates the actual degree of crosslinking.

The test was repeated using a similar base gel and a crosslinking agent. However, a certain amount of the bishydroxyethylglycine retention agent was injected immediately after the injection of the crosslinking agent. The vortex cessation time was recorded in a similar manner. The results for crosslinking compositions are presented below.

Record 1: 0.2% tetramethylammonium chloride of the total weight of the entire composition was used as a clay stabilizer.

A record of 2: 30 pounds / 1000 gallons of base carboxymethyl cellulose gel (CMC) prepared in 1 gallon / 1000 gallons of a 50% solution of TMAC in water was used to measure the vortex cessation time at pH 4.

A record of 3: 20 pounds / 1000 gallons of base carboxymethyl cellulose gel (CMC) prepared in 1 gallon / 1000 gallons of a 50% solution of TMAC in water was used to measure the vortex cessation time at pH 5.

A record of 4: 60 pounds / 1000 gallons of carboxymethylhydroxypropyl guar (CMHPG) base gel was used to measure vortex cessation time at pH 10.

Example 1

A 500 ml flask equipped with a thermocouple, dropping funnel, nitrogen drain and condenser was charged with 200 g of tetra-n-propyl zirconate solution in n-propyl alcohol containing 20.7% Zr (available from EI du Pont de Nemours and Company). Stirring was started and 135.3 g of triethanolamine was added. The mixture was heated to 60 ° C and held for 2 hours. In the next step, 62.3 g of tetrakis- (2-hydroxypropyl) ethylenediamine (Quadrol® polyol, available from BASF Corp.) and a mixture of 21 g of glycerol and 21 g of water were added. The solution was stirred for another 2 hours at a temperature of 60 ° C to obtain 439 g of an orange solution containing 9.3% Zr.

Example 2

A 500 ml flask equipped with a thermocouple, dropping funnel, nitrogen vent and condenser was charged with 313.7 g of a zirconium tetratriethanolamine complex (available from E.I. du Pont de Nemours and Company). Stirring was started and 132.6 g of tetrakis- (2-hydroxypropyl) ethylenediamine was added. The solution was stirred for 2 hours at a temperature of 60 ° C to obtain 446 g of an orange solution containing 9.3% Zr.

Examples 3-14

The method of example 2 was repeated for examples 3-14. In each example, 313.7 g of zirconium tetratriethanolamine complex was added. The amounts of Quadrol® polyol reagent, glycerol, and water added in each example are shown in Table 1.

Table 1 Example Quadrol® polyol, g Glycerin, g Water g 3 132.6 42 42 four 66.3 21 42 5 132.6 21 21 6 66 21 21 7 132.6 21 8 132.6 21 9 132.6 21 42 10 132.6 42 eleven 132.6 42 21 12 132.6 42 13 66.3 21 fourteen 66.3

The vortex cessation time was measured for the compositions of each of Examples 1-14. Moreover, the vortex cessation time was measured for a commercial product, a zirconium tetratriethanolamine complex, Tyzor® TEAZ organic zirconate. The vortex cessation time was measured at pH 4 and at pH 5 using the vortex cessation test in accordance with the above entries 2 and 3. The number of components and the results obtained are presented below in table 2.

table 2 Vortex cessation time measured at pH 4 and pH 5 Example No. Zr,% Zr ^a Tea ^b HPED ^c Glycerol Water gpt ^d Vortex cessation time (min) gpt ^d Vortex cessation time (min) mole mole mole mole mole pH 4 pH 5 Zr-tea ^e 13,2 one four 0 0 0 0.32 10 a.m. 0.48 0:32 one 9.3 one 2 0.5 0.5 2.5 0.68 1:19 1,04 1:12 2 9.3 one four one 0 0 0.44 0:53 0.68 0:01 3 7.8 one four one one 5 0.52 1:02 0.80 0:55 four 8.9 one four 0.5 one 5 0.48 1:14 0.80 3:28 5 8.5 one four one 0.5 2.5 0.48 0:48 0.72 1:02 6 9.8 one four 0.5 0.5 2.5 0.44 0:40 0.64 1:07 7 8.9 one four one 0 2.5 0.48 0:23 0.68 0:03 8 8.9 one four one 0.5 0 0.48 0:51 0.68 0:31 9 8.1 one four one 0.5 5 0.52 0:37 0.76 0:59 10 8.5 one four one one 0 0.48 2:34 0.72 0:41 eleven 8.1 one four one one 2.5 0.52 1:27 0.76 0:24 12 8.5 one four one 0 5 0.48 0:38 0.72 0:01 13 10.3 one four 0.5 0.5 0 0.40 1:18 0.60 0:17 fourteen 10.9 one four 0.5 0 0 0.38 2:16 0.56 0:10 ^and Zr refers to the molar amount of the zirconium complex prepared in accordance with each of Examples 1-14, and to the molar amount of the commercial zirconium tetratriethanolamine complex used in the test.
^b TEA - triethanolamine.
^c HPED - tetrakis- (2-hydroxypropyl) ethylenediamine (Quadrol® polyol reagent purchased from BASF Corp.).
^d gpt - means the number of gallons per thousand gallons.
^e Zr-TEA - zirconium tetratriethanolamine complex.

Table 2 shows that with an increase in the level of hydroxyalkylethylenediamine, tetrakis- (2-hydroxypropyl) ethylenediamine, HPED as long as the glycerol and water levels are kept constant, the crosslinking speed increases for both pH 4 and pH 5. Increasing the water level, while the HPED levels of polyhydric alcohol and glycerol are kept constant, it leads to an increase in the crosslinking rate at pH 4, with little effect at pH 5. Keeping the HPED levels of polyhydric alcohol and water constant and an increase in glycerol level, however, decreases by crosslinking speed. Therefore, by appropriately selecting the level of the used HPED polyhydric alcohol, glycerol and water, the crosslinking speed can be adjusted to accelerate or decelerate in order to correctly select the desired speed for a particular application.

Comparative Example A

352 g (0.799 mol) of tetra-n-propyl zirconate were charged into a 1000 ml flask equipped with a stirrer, condenser, dropping funnel, thermocouple and nitrogen vent. Stirring was started and 230.8 g (0.83 mol) of hydroxyethyl-tris- (2-hydroxypropyl) ethylenediamine, commercially available from Tomen Corporation, Tokyo, Japan, were added. The reaction mass was heated to a temperature of 60 ° C and kept for 2 hours. At the final stage of the aging period, the reaction mass was cooled to room temperature, which led to the formation of a pure yellow viscous liquid containing 12.3% Zr.

Comparative Example B

A 1000 ml flask equipped with a stirrer, condenser, dropping funnel, thermocouple and nitrogen vent was charged with 364 g (0.826 mol) of tetra-n-propyl zirconate. Stirring was started and 493.4 g (3.3 mol) of triethanolamine was added. The reaction mass was heated to a temperature of 60 ° C and kept for 2 hours. At the final stage of the aging period, a pressure of 20 mm Hg was applied in vacuo and the released n-propanol was removed. The reaction mass was then cooled to room temperature, resulting in a clear yellow viscous liquid containing 13.2% Zr.

Comparative Example C

368.6 g (0.609 mol) of a 30% zirconium oxychloride solution were charged into a 1000 ml flask equipped with a stirrer, condenser, dropping funnel, thermocouple and nitrogen vent. Stirring was started and 40 g (0.83 mol) of water was added. In the next step, 181.3 g (1.770 mol) of 85% lactic acid were quickly added during high-speed stirring while the temperature was maintained at 20-30 ° C. The reaction mass was stirred for an additional hour at a temperature of 20-30 ° C and then neutralized to a pH of 6.7-7.3 with a 25% aqueous solution of sodium hydroxide. The reaction mass was then heated to a temperature of 80 ° C and kept for 4 hours. At the final stage of the aging period, the reaction mass was cooled to room temperature, which led to the formation of a pale yellow-yellow clear liquid containing 5.4% Zr.

The vortex cessation time was measured for the compositions of each of comparative examples AC both for crosslinkable compositions and additionally for the compositions of examples 2, 7, 8, 10 and 12. The vortex cessation time was measured at pH 10 using the vortex cessation test as described above 4. For higher temperature applications, base gel fluids with a higher polymer loading amount (50-60 pounds / 1000 gallons) and a higher pH value (pH 9-11) are typically used. Under these conditions, the crosslinking speed in the vortex cessation test is in most cases preferred between 1 minute and 5 minutes. The number of components and the results are presented below in table 3.

Table 3 Vortex cessation time measured at pH 10 Example Zr,% Zr ^a Tea ^b HPED ^c Glycerol Water gpt ^d Vortex measurement time (min) mole mole mole mole mole pH 10 Comparative Example A 12,4 1.44 > 10 Comparative Example B 13,2 one four 0 0 0 1:36 0:14 Comparative Example C 5,4 3:36 0.05 2 9.3 one four one 0 0 1.92 1:05 7 8.9 one four one 0 2.5 2.0 2:16 8 8.9 one four one 0.5 0 2.0 3:35 10 8.5 one four one one 0 2:08 2:56 12 8.5 one four one 0 5 2:12 4:28 ^and Zr refers to the molar amount of the zirconium complex obtained in accordance with each of Examples 1-14, and to the molar amount of the commercial zirconium tetratriethanolamine complex used in the test.
^b TEA - triethanolamine.
^c HPED - tetrakis- (2-hydroxypropyl) ethylenediamine (Quadrol® polyol reagent purchased from BASF Corp.).
^d gpt means the number of gallons per thousand gallons.

From table 3 it can be seen that with the right selection of the levels of tetrakis- (2-hydroxypropyl) ethylenediamine, glycerol and / or water, the crosslinking composition of this invention guarantees a crosslinking time in the desired time range of 1-5 minutes. Table 3 also shows comparative zirconium crosslinking compositions that do not contain a complex of zirconium triethanolamine and tetra (hydroxyalkyl) ethylenediamine, having a vortex termination time that is either too fast or too slow.

Claims (13)

1. A crosslinking composition comprising a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and optionally a polyhydric alcohol. 2. The composition according to claim 1, in which the zirconium complex is bistriethanolamine zirconate or tetratriethanolamine zirconate. 3. The composition according to claim 1, in which the tetra (hydroxyalkyl) ethylenediamine has the formula R ¹ (R ² ) -N-CH ₂ -CH ₂ -N′-R ³ (R ⁴ ), where R ¹ , R ² , R ³ and R ^{4 are} independently selected from the group consisting of hydroxyethyl, hydroxy-n-propyl or hydroxyisopropyl groups. 4. The composition according to claim 3, in which the tetra (hydroxyalkyl) ethylenediamine is selected from the group consisting of N, N, N ′, N′-tetrakis- (hydroxyisopropyl) ethylenediamine and N, N, N ′, N′-tetrakis- (2-hydroxyethyl) ethylenediamine and combinations thereof. 5. The composition according to claim 4, additionally containing a polyhydric alcohol selected from the group consisting of glycerol, 1,1,1-tris (hydroxymethyl) ethane, 1,1,1-tris (hydroxymethyl) propane, penta-erythritol and sorbitol . 6. The composition according to claim 2, additionally containing a restraining agent, which is hydroxyalkylaminocarboxylic acid. 7. The composition according to claim 2, additionally containing an organic polymer capable of crosslinking, selected from the group consisting of soluble polysaccharides, polyacrylamides and polymethacrylamides. 8. The composition according to claim 2, additionally containing a pH buffer. 9. A method of hydraulically fracturing an underground formation, comprising introducing into the formation a crosslinking composition comprising a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water, a crosslinkable organic polymer, and optionally a polyhydric alcohol, at a flow rate and pressure sufficient to create a second the opening and / or enlargement of one or more cracks in the formation. 10. A method of tearing an underground formation, including:
(a) preparing a base gel by mixing an organic polymer that is crosslinkable with a solvent, said solvent being water or a water / organic solvent mixture or an aqueous solution;
(b) preparing a crosslinking composition by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and optionally a polyhydric alcohol;
wherein optionally a retention agent, a pH buffer, or both are added to the base gel, crosslinking composition, or both;
(c) contacting the base gel with a crosslinking composition;
(d) allowing the base gel and the crosslinking composition to react to form a crosslinked aqueous gel; and
(e) introducing a crosslinked gel into the formation at a flow rate and pressure sufficient to re-open and / or increase the fracture in the formation. 11. A method of fracturing an underground formation passed by a borehole, which includes:
(a) preparing a crosslinking composition by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and optionally a polyhydric alcohol;
(b) preparing a base gel by mixing an organic polymer that is crosslinkable with a solvent, wherein the solvent is water or a water / organic solvent mixture, or with an aqueous solution;
(c) introducing a base gel into a borehole;
(d) simultaneously with or sequentially after the introduction of the base gel into the borehole, the introduction of a crosslinking composition into the borehole;
(e) allowing the base gel and the crosslinking composition to react to form a crosslinked aqueous gel; and
(f) introducing a crosslinked gel into the formation through a borehole at a flow rate and pressure sufficient to create re-opening and / or widening the fracture in the formation. 12. A method of plugging a permeable zone and / or seeping into an underground formation, comprising introducing into the permeable zone or subterranean seepage area a crosslinking composition comprising a zirconium triethanolamine complex, tetra (hydroxyalkyl) ethylenediamine, water, a crosslinkable organic polymer, and optionally polyhydric alcohol . 13. A method of plugging a permeable zone and / or seeping into an underground formation, including:
(a) preparing a crosslinking composition by mixing a complex of zirconium triethanolamine, tetra (hydroxyalkyl) ethylenediamine, water and optionally a polyhydric alcohol;
(b) preparing a base gel by mixing an organic polymer that is crosslinkable with a solvent, the solvent being water or a water / organic solvent mixture, or with an aqueous solution;
(c) introducing a base gel into a permeable zone or an area of underground seepage;
(d) simultaneously with or sequentially after introducing the base gel into the permeable zone or subterranean seepage area, introducing the crosslinking composition into the permeable zone or subterranean seepage area;
(e) allowing the base gel and the crosslinking agent to react to form a crosslinked aqueous gel to clog the zone or leak out.